Air spinning method for the production of large yarns with count lower than ne20 and relative yarn

ABSTRACT

An air spinning method comprising the steps of:
         preparing at least one web of textile fibers (N 1 ), to be fed by at least one introducer element ( 24 ) upstream of an air spinning device ( 28 ),   drawing said at least one web (N 1 ) with at least one drawing device ( 32 ),   feeding said web (N 1 ), previously drawn, in a spinning chamber ( 36 ) of the air spinning device ( 28 ),   spinning the fibers ( 12 ) inside the spinning chamber ( 36 ) by means of compressed air jets, so as to:   obtaining a yarn ( 4 ) comprising internal fibers ( 20 ) surrounded by external fibers ( 16 ),   wherein the yarn ( 4 ) has an overall thread count lower than Ne20 and wherein the total number of internal ( 20 ) and external ( 16 ) fibers is less than 200.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention claims priority to Italian Patent Application No.102018000010751 filed on Dec. 3, 2018.

FIELD OF APPLICATION

The present invention relates to an air spinning method for theproduction of yarns with a count lower than or equal to Ne20 and greaterthan or equal to Ne10, and a relative yarn obtained with said method.

PRIOR ART

In particular, the air spinning of yarns having lower counts than Ne20is complicated since the tenacity and regularity of the yarn tend todecrease drastically when making yarns with such low counts.

The yarns that are normally processed on air-spinning machines are PES,Viscose (and its modal, tencel variants, etc.), cotton and the variouscompounds.

The prior art of the production of such yarns involves the use of highquality fiber webs, that is with an average length of 38 mm and fiberdiameter between 1.3 and 1.5 dtex for artificial fibers and, in the caseof cotton, with micronair lower than 4.2.

An empirical formula defines the following link: micronair=2,824deniers=2,824*1,111 dtex; so it follows that: dtex=micronair/3,135.

The commonly accepted idea in the art is that in air spinning machinesit is necessary to have many fibers, indeed, as many fibers as possibleto obtain yarn with high strength and elasticity.

The formula that calculates the number of fibers per section is given asfollows:

Number_fibers_section=5917/(Yarn_Count (Ne)*fibre count(dtex))=15030/(Yarn_Count (Ne)*micronair(μ).

Clearly the first formula can be used in the case of artificial fibers,the second for cotton.

There are even formulas of the American Ministry of Agriculture whichprovide the maximum tenacity that can be reached in spinning as afunction, among the various parameters, of the number of fibers thatcontribute to the formation of the yarn.

This formula of the American FDA, valid for ring cotton carded yarns isthe following:

cN/tex)=(1/count (Ne))*(19−52*Count (Ne)+6618*Fiber_length(Inches)−236*micronair(μ)+51*Fiber_resistance(g/tex).  Expected_Yarn_Resistance

From the above formula, considering that lower micronair values meanlonger and more resistant fibers, it is evident that greater resistancesare obtained with lower micronairs.

Therefore, summarizing, the idea of increasing the number of fibers inyarns in order to improve the strength and elasticity of the yarnproduced is known and consolidated in the art.

Thus the idea of making yarns with a high count, with a high number offibers, in which said fibers are relatively thin, to increase theirmechanical strength, is consolidated in the art.

It has instead been verified that this solution, in the case ofapplications with air spinning, does not always give the optimumcompromise between strength and quality of the yarn thus obtained.

DISCLOSURE OF THE INVENTION

The need to solve the drawbacks and limitations mentioned with referenceto the prior art is therefore felt.

Such a need is met by an air spinning method according to claim 1 and bya yarn obtained by the air spinning according to claim 4.

DESCRIPTION OF THE DRAWINGS

Further features and advantages of the present invention will appearmore clearly from the following description of preferred non-limitingembodiments thereof, in which:

FIG. 1 shows a schematic view of an air spinning device for implementinga spinning method according to an embodiment of the present invention;

FIGS. 2a, 2b, 2c show a view, with increasing magnifications, of a yarnmade with air spinning, of the prior art;

FIGS. 3a-3b show schematic sectional views of two yarns obtainedaccording to the method of the present invention and according to theteachings of the prior art, respectively.

Elements or parts of elements in common to the embodiments describedbelow are referred to with the same reference numerals.

DETAILED DESCRIPTION

With reference to the aforesaid figures, reference numeral 4 indicates ayarn, in particular obtained by means of an air spinning, preferablywith multiple feeding.

The present invention finds application in particular in the use onman-made/synthetic fibers and possibly fibers mixed with cotton, but not100% cotton.

The yarn 4 comprises a plurality of threads 8 each comprising aplurality of fibers 12.

By analyzing the threads 8 in section, a plurality of fibers 12 can beseen which can be divided into external fibers 16 and internal fibers20.

The internal fibers 20 are those which constitute the core of the thread8 in turn surrounded by the external fibers 16.

Advantageously, the present invention provides to obtain yarns 4 with anoverall number of fibers 12 lower than a maximum value, preferably equalto 200.

Advantageously, it has been found that it is useful to use thickerfibers as the yarn count decreases, so as to keep the total number offibers 12 ideally below the aforementioned maximum value, preferablyequal to 200.

The optimum is to have a number of fibers 12 sufficient to givesubstance to the thread 8 but not too high to worsen its technicalfeatures.

All this is due to the fact that, in air spinning, there is no realtwist as in traditional ring spinning: rather, in air spinning, bundlesof fibers are obtained that are wound more or less regularly around acore of “neutral” central fibers, that is, substantially not twisted.

Therefore in the air spinning it has been verified that the externalfibers 16 are twisted, while the internal fibers 20 are neutral as caneasily be seen in FIGS. 2a, 2b and 2 c.

Typically, in the solutions of the prior art, a yarn Pes 100% of countNe20, produced with air spinning machines, has a fiber length of 38 mmand a section of 1.3 dtex and contains about 227 fibers.

A yarn Ne16 of the prior art, with the same raw material, would contain285 fibers.

The solution of the present invention provides instead to maintain thefibers 12 under 200 units (maximum value) and the reason is shown inFIGS. 3a , 3 b.

In fact, in air spinning only the outermost fibers 16 are involved inthe “twisting” while the central or internal ones 20 remainsubstantially neutral. This means that the ratio between external fibers16 and internal fibers 20 must remain high, in order to have a yarn withadequate mechanical features.

Regardless of the count being worked, it can be said that the number ofexternal fibers that are involved in the twisting always remains thesame, which is why the more fibers are in the section, the moreunfavorable, that is, low, the ratio between external fibers (twisted)and internal fibers (not twisted).

In the accompanying figures (3 a, 3 b), a yarn with a count Ne20 isideally represented, made with 1.5 dtex fibers (FIG. 3a ) and 1.0 dtexfibers (FIG. 3b ). It is clearly seen that in the first case (FIG. 3a ),having fibers of an average greater diameter, the number of externalfibers 16 or twisted, which are wound, with respect to the internal ones20 which remain neutral, is much higher than in the second case (FIG. 3b), where the individual fibers 12 (whether they are external fibers 16or internal fibers 20) have a lower average diameter.

The present invention (FIG. 3a ), as the counts decrease, provides toincrease the section of the fibers 12 used and therefore reduce thetotal number thereof, to a maximum value preferably equal to 200.

This section increase becomes extremely useful in synthetic fibers wherethe value of the elongation at break increases with the increase in thesection of the fibers, with obvious benefits in the final yarn: moreresistance and more elasticity mean greater quality and workability ofthe same yarn.

The air spinning method provides the steps of preparing at least one webof textile fibers N1, to be fed by at least one introducer element 24upstream of an air spinning device 28.

The web N1 is previously drawn with at least one drawing device 32, andthen, after drawing, said web N1 is fed into a spinning chamber 36 of anair spinning device 40.

Inside the spinning chamber 36 the fibers 12 are spun by means of jetsof compressed air, so as to obtain a yarn F comprising internal fibers20 surrounded by external fibers 16, in which the yarn has an overallcount lower than or equal to Ne20 and greater than or equal to Ne10, andin which the total number of internal and external fibers is less than200.

In particular, the working pressures, i.e. the jets of compressed airinside the spinning chamber 36, are preferably between 0.45 and 0.6 MPa,i.e. between 4.5 and 6 bar.

The working speeds of the compressed air leaving the relative nozzlesare comprised between 400 m/min and 500 m/min.

Obviously, it is possible to feed two or more webs N1, N2, withrespective introducer elements 24, into the air spinning device 28:these webs are joined together inside the spinning chamber 36.

As can be seen from the above description, the air-jet spinning methodaccording to the invention allows the drawbacks of the prior art to beovercome.

In particular, the present invention allows obtaining, by means of airspinning, yarns with a count lower than or equal to Ne20 and greaterthan or equal to Ne10. These yarns have features of resistance andelasticity which are superior to the solutions obtainable with themethods of the prior art.

In fact, as seen, as the counts decrease, it is provided to increase thesection of the fibers used and therefore reduce the total numberthereof, to a maximum value preferably equal to 200.

In this way, increasing the average diameter of the fibers, the numberof external fibers, twisted, which are wound, with respect to theinternal ones which remain neutral, is much higher: this aspectdetermines the improvement of the mechanical features of the yarnobtained.

Moreover, as seen, the section increase becomes extremely useful insynthetic fibers where the value of the elongation at break increaseswith the increase in the section of the fibers: therefore moreresistance and more elasticity are obtained and, consequently, evengreater quality and workability of the same yarn.

Substantially, the present invention goes against the known andconsolidated idea in the art of increasing the number of fibers in yarnsin order to improve the strength and elasticity of the yarn produced.The present invention teaches exactly the opposite, namely to decreasethe number of fibers in the yarns, increasing their average size, inorder to improve their mechanical and workability features. Suchteaching finds advantageous application in the air-jet spinning sector.

In order to satisfy contingent and specific needs, a man skilled in theart will be able to make numerous modifications and variations to theair spinning methods for mixed yarns described above, all of which fallwithin the scope of the invention as defined by the following claims.

1. Air spinning method comprising the steps of: preparing at least oneweb of textile fibres, to be fed by at least one introducer elementupstream of an air spinning device, drawing said at least one web withat least one drawing device, feeding said web, previously drawn, in aspinning chamber of the air spinning device, spinning the fibres insidethe spinning chamber by means of compressed air jets, so as to: obtain ayarn comprising internal fibres surrounded by external fibres, whereinthe yarn has an overall thread count not exceeding Ne20 and wherein thetotal number of internal and external fibres is less than
 200. 2. An airspinning method according to claim 1, wherein said overall thread countis greater than or equal to Ne10.
 3. An air spinning method according toclaim 1, wherein the method comprises the step of increasing the averagecross-section or diameter of the fibres of the yarn gradually as theyarn count of the yarn to be produced decreases, so as to maintain thetotal number of internal and external fibres below
 200. 4. An airspinning method according to claim 2, wherein the method comprises thestep of increasing the average cross-section or diameter of the fibresof the yarn gradually as the yarn count of the yarn to be produceddecreases, so as to maintain the total number of internal and externalfibres below
 200. 5. Air spinning method according to claim 1, whereinthe method comprises the steps of preparing two textile fibre webs, tobe fed by at least one corresponding introducer element upstream of theair spinning device, drawing each of said webs with at least one drawingdevice, joining said webs inside the spinning chamber and spinning thefibres so as to obtain a yarn with a total thread count of less thanNe20 and wherein the total number of internal and external fibres isless than
 200. 6. Air spinning method according to claim 2, wherein themethod comprises the steps of preparing two textile fibre webs, to befed by at least one corresponding introducer element upstream of the airspinning device, drawing each of said webs with at least one drawingdevice, joining said webs inside the spinning chamber and spinning thefibres so as to obtain a yarn with a total thread count of less thanNe20 and wherein the total number of internal and external fibres isless than
 200. 7. Air spinning method according to claim 3, wherein themethod comprises the steps of preparing two textile fibre webs, to befed by at least one corresponding introducer element upstream of the airspinning device, drawing each of said webs with at least one drawingdevice, joining said webs inside the spinning chamber and spinning thefibres so as to obtain a yarn with a total thread count of less thanNe20 and wherein the total number of internal and external fibres isless than
 200. 8. Air spinning method according to claim 1, wherein theworking pressures, i.e. of the compressed air jets inside the spinningchamber, are between 0.45 and 0.6 MPa.
 9. Air spinning method accordingto claim 1, wherein the working speeds of the compressed air in outputfrom relative nozzles, inside the spinning chamber, are between 400m/min and 500 m/min.
 10. The yarn obtained by means of a spinning methodaccording to claim
 1. 11. The yarn according to claim 7, wherein saidyarn has an overall thread count of less than Ne20 and wherein the totalnumber of inner and outer fibres of the yarn is less than
 200. 12. Theyarn according to claim 7, wherein said overall thread count is greaterthan or equal to Ne10.
 13. The yarn according to claim 8, wherein saidoverall thread count is greater than or equal to Ne10.